[en] Improving dairy cow fertility by means of genetic selection has become increasingly important over
the last years in order to overcome the declining cow fertility. This study investigated whether the
fatty acids profile in milk could be used as an early predictor of genetic merit for fertility. Genetic
covariances among 17 fatty acid contents in milk and the number of days from calving to conception
were estimated from 29,792 first-parity Holstein cows. Results substantiated the unfavorable
relationship among fertility and body fat mobilization in early lactation. Also, about 75% of the
genetic variability of fertility was explained by the variability in milk fatty acids profile over the
lactation indicating that these traits could be used to supplement genetic evaluations for fertility.